I use a software program called Market Samurai, to find the best keywords to target. I think you should give it a try!
I use a combination of keyword tools and reports but one of the best is Google's Adwords keyword tool. If I am selling a product I compare to several product related sites and reports. It depends on what I am trying to do.
I use both paid and free keyword tools. One way is to find the site that is listed in the number one spot and conduct a Google keyword search for that site. You will get all the keywords that site is using and you can use those same keywords.
seobooks keyword duggestor will give u long tail searches, some as long as 7 or 8 words but only if they are in the top 1000 for any term u enter googles keyword tool seems to pretend many obvious long tail seraches don't exist / have zero volume but i'm not sure why.
Good keywords are frequently searched for (high demand) but not being targeted by many other websites (low competition). There are 3 tools out there that can help you find them. The best tool out there, Wordtracker14 is one of the most essential SEO tools. Also very useful, Google AdWords Keyword Tool21 is free and much quicker to use than Wordtracker. KeywordSpy22 is an interesting resource. Type in a keyword phrase and it'll tell you which websites are targeting that phrase.
google keywords tool is that good. sometimes you found a word with high monthly searches, but you still can not get much traffic though that word in your site page ranks well in google.